Right – it doesn’t look like they are compatible (I think)
MotionX deals with tracks (trk) which are just a collection of points (trkpt) every few seconds like this:
<trk>
<name>Wylam wood Road</name>
<desc>16 Apr 2011 12:26 pm</desc>
<trkseg>
<trkpt lon="-1.829131" lat="54.971664">
<ele>8.371592</ele>
<time>2011-04-16T11:26:38Z</time>
</trkpt>
<trkpt lon="-1.829131" lat="54.971664">
<ele>12.166491</ele>
<time>2011-04-16T11:26:54Z</time>
</trkpt>
...
Whereas Cycle Streets produces a route (rte) which is basically a series of waypoints (rtept) like this:
<rte>
<name>Balanced Algernon Terrace to Sunderland Road</name>
<desc>Balanced cycle journey from Algernon Terrace to Sunderland Road</desc>
<rtept lon="-1.823186" lat="54.977043">
<name>Cherry Tree Lane</name>
</rtept>
<rtept lon="-1.822657" lat="54.976395">
<name>Main Road</name>
</rtept>
<rtept lon="-1.820677" lat="54.976482">
<name>Main Road</name>
</rtept>
<rtept lon="-1.819329" lat="54.976158">
<name>Falcon Terrace</name>
</rtept>
The good news is that there is also a Cycle Streets phone app so you could maybe try using that?